The premise of this study is to conduct a Phase I/II study to evaluate the combined approach of calcitrol and prednisone in patients with advanced cancer. Vitamin D is a steroid hormone best known for its activity in regulating calcium and bone metabolism. The active form of vitamin D is calcitriol [1,25-(OH) 2D3]. Epidemiologic evidence suggests that calcitriol may play an important role in the development of colon and prostate cancer. Preclinical studies of cancer cell lines have shown that calcitriol can kill tumor cells.